Field of the Invention
The present invention relates to a processing apparatus that performs a process (such as a calcination process) to secure the particles in a particle dispersed liquid onto a base material, and a particle securing method using the processing apparatus.
Description of the Related Art
In manufacturing printed circuit boards, membrane switches, and electrode units of electronic devices and the like, a subtractive process involving etching is conventionally used. However, a subtractive process requires a large number of complicated steps and a lot of equipment. In addition to that, a subtractive process has low efficiency in the use of material, resulting in high production costs.
As a manufacturing method that can solve these problems with a subtractive process, so-called printed electronics (PE) is drawing attention these days. In PE, a particle dispersed liquid in which metal nanoparticles or the like having electrical functions are dispersed is applied onto a base material by a printing technique. In PE, the particle dispersed liquid applied onto the base material is calcined, so that the particles are secured onto the base material.
Specifically, after the particle dispersed liquid is applied onto the base material, the solvent and the dispersant are removed from the particle dispersed liquid by action of heat, light, chemical energy, or the like. As a result, the particles are bonded to one another, and are secured as a film having the function of the particles onto the base material. If the amount of calcination energy supply is too small when such a calcination process is performed, the solvent, the dispersant, or non-bonded particles remain, and the function of the formed film cannot be sufficiently achieved, resulting in defective conduction or the like. If an excessive amount of calcination energy is supplied, on the other hand, the base material might be damaged.
So as to avoid such problems, a method of controlling calcination conditions through a comparison with the absolute value of an already measured amount of light reflected from a test pattern has been suggested (see JP 2008-225093 A, for example).
According to the technique disclosed in JP 2008-225093 A, however, variations appear in the molten state and the bonding state of the particles due to variations in respective conditions, and, in some cases, it is difficult to perform calcination by the right amount. The respective conditions may include the attachment position of the detector, the attachment position of the light source, temporal or spacial fluctuations in the amount of light emitted from the light source, the pattern to be formed, the type and the thickness of the base material, the amount of discharged ink, the type and the amount of ink, environmental conditions, and the like.
JP 63-73628 A discloses a technique of determining the state of a liquid based on a relative value of a detection signal, not on the absolute value of the detection signal. However, by the technique disclosed in JP 63-73628 A, only the existence of a liquid is detected, and particle binding and other phenomena cannot be detected.